Process for the production of cyanoacetic acid

ABSTRACT

Cyanoacetic acid is prepared from a cyanoacetic ester by said hydrolysis with aqueous hydrochloric acid in a molar ratio of 1: 0.25 - 0.55 at a temperature of 50* - 100*C.

awllt [1 1 Barbezat et al.

[ PRUCESS FOR THE PRODUCTION OF CYANfiACETllC AC [75] Inventors: PierreBarbezat; Colm 0. Murchu,

both of Visp, Switzerland [73] Assignee: Lama Ltd Gampel/Valais,Switzerland [22] Filed: June 18, 1971 [21 Appl. No.: 154,683

[30] Foreign Application Priority Data June 19, 1970 Switzerland..9301/70 [52] US. Cl. ..260/465.4 [51] Int. Cl ..C07c 121/40 [58] Fieldor Search ..260/465.4

[56] References Cited UNITED STATES PATENTS 3,577,455 5/1971 Jones etal. ..260/465.l X 2,338,834 1/1944 Britton et a1. ..260/465.4

1 Mar. 27, 3973 OTHER PUBLICATIONS Groggins; Unit Processes in OrganicChemistry, (1958), page 753 Migrdichian; Organic Synthesis, Vol.- 1,(1957) pages 336-337 Noller; Chemistry of Organic Compounds, 2nd ed.1957 page 170 Kan-er; Organic Chemistry, (1950) page 212 Trakhtenberg etal., C.A., (38), 1944, page 3248 Inglis; Org. Syn. Coll. Vol. 1, (1941)pages 254-256 Phelps, et a]., CA. (3), 1909, page 1533 Phelps, et a1.,C.A., (3), 1909, page 1534 Primary Examiner-Joseph P. BrustAttorney-Eric H. Waters et a1.

57 ABSTRACT Cyanoacetic acid is prepared from a cyanoacetic ester bysaid hydrolysis with aqueous hydrochloric acid in a molar ratio of 1:0250.55 at a temperature of 50 100C.

6 Claims, No Drawings PROCESS FOR THE PRODUCTION OF CYANOACETIC ACIDBACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates to a process for the production of cyanoacetic acid from acyanoacetic ester by acidic hydrolysis.

2. Prior Art It is known to prepare cyanoacetic acid from cyanoaceticester by acidic hydrolysis with nitric acid. The yields amount to about88 percent, the degree of purity of the obtained yellowish produce isonly 88.5 percent (Chemical Abstracts 38, 3248).

It is further known that cyanoacetic esters are converted into thecorresponding malonic esters with the aid of hydrochloric acid byhydrolysis of the CN group (Chemical Abstracts 3 (1909) 1,533-1,534). Ifthe process is carried out with concentrated hydrochloric acid, thespeed at which the nitrile group of the aliphatic nitriles is hydrolyzedis so high that the reaction is exothermic and must be moderated bycooling (Houben-Weyl, Vol. 8, page 429).

It is also known that free cyanoacetic acid can be liberated from itssodium salt by means of hydrochloric acid. In this operation,temperatures above 60 70C must be avoided, since otherwise decompositionof the cyanoacetic acid occurs (org. Synt. Coll. Vol. 1, pages 254-255).

DETAILED DESCRIPTION The present invention has for an object thepreparation of cyanoacetic acid from a cyanoacetic ester with such ahigh degree of purity that additional purification can be dispensedwith. This is achieved according to.

the invention by treating the cyanoacetic ester with aqueoushydrochloric acid in a molar ratio of 1:0.25-0.5S based on I-ICl, at atemperature of 50 100C.

The alcohol moiety in the cyanoacetic ester is an alkyl group,preferably with one to six carbon atoms.

A molar ratio of cyanoacetic ester to I-ICl of 1:0.35 0.45 and atemperature of 80- 100C is preferred.

It is expedient to adjust the concentration of the aqueous hydrochloricacid in such a way that -15 mol of water are present in the reactionmixture for every mol of cyanoacetic ester.

When the reaction is completed (after about 10 minutes), the water andthe hydrochloric acid are EXAMPLE 99 g (1 mol) of cyanoacetic acidmethyl ester were heated with 200 ml of water and 0.4 mol ofhydrochloric acid at 80 90C for 10 minutes. The reaction mixture wassubsequently concentrated by evaporation in a gradually increasingvacuum.

The yield of cyanoacetic acid (degree of purity 97 percent) amounted to96.5 percent, referred to the pure product.

Cyanoacetic acid can similarly be prepared from other cyanoacetic esterswhere the alcohol moiety is other than methyl, for example, those estersof alcohols containing up to six carbon atoms.

What is claimed is:

1. A process for the production of cyanoacetic acid from a cyanoaceticester by acidic hydrolysis, comprising treating a cyanoacetic ester withaqueous hydrochloric acid in a molar ratio of 1:025 0.55, based onI-ICl, at a temperature of 100C in the presence of l0-l5 moles of waterper mole of cyanoacetic ester and wherein the alcohol moiety in theester is an alkyl group having one to six carbon atoms.

2. A process according to claim 1, wherein the molar ratio of thecyanoacetic ester to I-ICl is 110.35 0.45

3. A process according to claim 1 wherein the temperature is 80 100C.

4. A process according to claim 2 wherein the temperature is 80- 100C.

5. A process according to claim 1 wherein the cyanoacetic ester iscyanoacetic acid methyl ester.

6. A process according to claim 1 wherein the reaction mixture isevaporated under vacuum after completion of the reaction leaving acrystalline residue of cyanoacetic acid.

2. A process according to claim 1, wherein the molar ratio of thecyanoacetic ester to HCl is 1:0.35 - 0.45.
 3. A process according toclaim 1 wherein the temperature is 80* - 100*C.
 4. A process accordingto claim 2 wherein the temperature is 80* - 100*C.
 5. A processaccording to claim 1 wherein the cyanoacetic ester is cyanoacetic acidmethyl ester.
 6. A process according to claim 1 wherein the reactionmixture is evaporated under vacuum after completion of the reactionleaving a crystalline residue of cyanoacetic acid.